Optical constants
Refractive index of AuAl2 (Gold-aluminium intermetallic, Purple plague)
Supansomboon et al. 2008: n,k 0.300–1.32 µm
- Data
- tabulated nk
- Range
- 0.3–1.32 µm
- Points
- 35
- Licence
- CC0-1.0
Plot
Click the plot to set the calculator wavelength.
At one wavelength
- Refractive index n
- 1.20684
- Extinction coefficient k
- 1.52632
- Permittivity ε1
- -0.87319
- Permittivity ε2
- 3.68405
- Absorption coefficient α
- 326418 cm⁻¹
- Penetration depth δ = λ/(2πk)
- 61.2712 nm
- Abbe number Vd
- —
- Chromatic dispersion dn/dλ
- -1.6 µm⁻¹
- Group index ng
- 2.147
- Group velocity dispersion
- — fs²/mm
- Dispersion parameter D
- — ps/(nm·km)
- Photon energy
- 2.11001 eV
ε = (n + ik)², α = 4πk/λ, ng = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.
Use it in Lightsmith
Load this data in Python, simulate in one more line
pip install lightsmith
import lightsmith as ls
# AuAl2 (Gold-aluminium intermetallic, Purple plague): Supansomboon et al. 2008: n,k 0.300–1.32 µm
aual2 = ls.fetch_refractiveindex("other", "AuAl2", "Supansomboon", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(aual2.range_nm) # (300, 1320) nm
eps = aual2.eps([633]) # complex permittivity
Downloads the original record once (pinned to the imported snapshot) and caches it.
import json, urllib.request
import lightsmith as ls
url = "https://materials.lightsmith.dev/v1/datasets/ds_98778ef3c4f0/lightsmith"
aual2 = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(aual2.source) # citation and provenance travel with the data
Any dataset here, as the library's Tabulated material (aual2/supansomboon-2008).
# ... load aual2 as above, then:
sim = ls.Simulation(
particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=aual2)],
medium_index=1.0,
wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, num=81),
)
res = ls.solve(sim) # exact Mie for a sphere
print(res.q_ext) # extinction efficiency at each wavelength
Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).
Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.
Comments and conditions
References
- doi:10.1007/bf03214887 “Purple glory”: The optical properties and technology of AuAl2 coatings, Gold Bulletin (2008)
Cite
S. Supansomboon, A. Maaroof and M. B. Cortie. “Purple glory”: The optical properties and technology of AuAl2 coatings. Gold Bulletin, 41, 296-304 (2008), doi:10.1007/bf03214887; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)
Data
35 rows as published| λ (µm) | n | k |
|---|---|---|
| 0.3 | 2.058 | 1.499 |
| 0.33 | 2.084 | 1.722 |
| 0.36 | 2.042 | 1.863 |
| 0.39 | 1.842 | 1.872 |
| 0.42 | 1.644 | 1.785 |
| 0.45 | 1.43 | 1.639 |
| 0.48 | 1.35 | 1.503 |
| 0.51 | 1.289 | 1.406 |
| 0.54 | 1.275 | 1.407 |
| 0.57 | 1.235 | 1.47 |
| 0.6 | 1.187 | 1.566 |
| 0.63 | 1.117 | 1.717 |
| 0.66 | 1.057 | 1.874 |
| 0.69 | 1.007 | 2.042 |
| 0.72 | 0.97 | 2.21 |
| 0.75 | 0.944 | 2.372 |
| 0.78 | 0.93 | 2.532 |
| 0.81 | 0.921 | 2.686 |
| 0.84 | 0.914 | 2.836 |
| 0.87 | 0.907 | 2.985 |
| 0.9 | 0.9 | 3.13 |
| 0.93 | 0.899 | 3.273 |
| 0.96 | 0.901 | 3.412 |
| 0.99 | 0.905 | 3.548 |
| 1.02 | 0.919 | 3.682 |
| 1.05 | 0.936 | 3.814 |
| 1.08 | 0.953 | 3.946 |
| 1.11 | 0.971 | 4.075 |
| 1.14 | 0.993 | 4.201 |
| 1.17 | 1.02 | 4.325 |
| 1.2 | 1.049 | 4.446 |
| 1.23 | 1.077 | 4.562 |
| 1.26 | 1.107 | 4.676 |
| 1.29 | 1.141 | 4.789 |
| 1.32 | 1.178 | 4.898 |
Optical transmission calculator
Free-standing sample in vacuum, normal incidence- Transmittance T
- —
- Reflectance R
- —
Fresnel reflection calculator
- Rp
- —
- Rs
- —
- R = (Rp+Rs)/2
- —
- Phase φp
- —
- Phase φs
- —
- Brewster angle θB
- —
- Critical angle θC
- —
68 nm thick AuAl2 film produced by 8 min of sputtering. Room temperature.